Treatment of drilling fluids



Patented Apr. 26, 1949 TREATMENT OF DRILLING FLUIDS Milton Dyke, San Marino, and Edward Samuel Self, Bakersfield, Calm, asslgnors to Oil Well Chemical and Materials Company, Inc., Los Angeles, Calif., a corporation of California No Drawing. Application April 29, 1946, Serial No. 665,898

4 Claims. 1

This invention relates to the treatment of drilling fluids and particularly to the treatment of water based drilling fluids, such as are employed in the rotary drilling of oil wells.

In drilling wells by the rotary method, it is necessary to circulate a drilling fluid in the bore hole to lubricate the drill bit, to carry the cuttings up to the surface, to hold down the formation pressures, and to form on the walls of the bore hole a sheaf or cake which prevents the drilling fluid from escaping into the formation.

Drilling fluids of the water base type consist of a clay suspended in water to which weighting materials, such as bentonite, galena, iron oxide, etc., are sometimes added to increase the specific gravity of the mud. The mud may be madefrom the natural clay which occurs at the location of the well or may be synthetically compounded from the clay and mud bases of commerce, including bentonite and beidellite.

In order to perform its function as has been above noted, the composition and condition of 'the drilling fluid must be rather closely controlled, and that is particularly true of its water loss to the formation and its viscosity; for if the water loss be too high, the filter cake on the wall builds up to such an extent that circulation of the mud fluid between the drill pipe and the walls of the hole is greatly impeded. Still further reasons for keeping the filter loss at the lowest possible level are to prevent caving of the walls of the bore hole and, to obtain the best possible result when cementing the casing, a thin mud cake is desirable. Still another reason for keeping water loss at a minimum is that when contacting the oil sands, the escape of water from the drilling fluid into the oilsand blocks the flow of oil into the bore hole and thereby lessens production from the producing sands.

Referring to the importance of the control of viscosity of a drilling fluid as aforementioned, if the viscosity is too low, the cuttings will not be carried to the surface properly and freezing of the drill stem may take place; if the viscosity is too high, then the cuttings will not be properly deposited in the settling ditch or slush pit of the well, and moreover the drilling fluid column is likely to be gas-cut"; that is, become permeated with gas from the formation being drilled. For

practical purposes, the viscosity is usually maintained at between about and 55 centipoises, as measured on a Stormer viscosimeter.

A drilling fluid of low water loss and of proper viscosity may change appreciably as to both of these important characteristics during use. The

drilling of the formation causes cuttings to enter the fluid and these cuttings may include salts or materials which increase the water loss of the drilling fluid and also increase its viscosity. The salts that seem to be particularly offensive in such regard are those of calcium and magnesium.

A still further source of contamination to the drilling fluid is that brought on by cementing a formation and a subsequent drilling operation through the cement. v

One of the objects of this invention therefore is to provide a drilling fluid and a treatment for a drilling fluid for effectively lowering the water loss of said fluid.

Another object is to provide a process for trcat ing drilling fluids in order to reduce the 'water loss of said fluids.

A. still further object is to provide a treatment for a drilling fluid having the combined effect of reducing the water loss of said drilling fluid and the viscosity thereof.

A still further object of this invention is to provide an improved process for the treatment of drilling fluids with the chemical agents herein after set forth.

Still another object is to provide a drilling fluid which has improved qualities and characteristics adapting it particularly to the function of lubricating the drilling bit.

Further objects will appear from the description to follow, and it is understood that modifications thereof are included within the scope of the invention as set out in the appended claims.

One or more of the aforesaid objects may be accomplished by incorporating a small amount of a tall oil soap into a water base drilling fluid.

As an example of our invention, 40% by weight of tall oil was heated with by weight of water and 5% by weight of caustic soda flakes at a temperature of Fahrenheit for a period of about 30 minutes. This procedure produced a liquid soap which was then used in accordance with the process of our invention.

Six per cent (6%) by volume of a soap so produced was added to a drilling fluid which was being used in a drilling well in the Seal Beach field at Seal Beach, California. Prior to the addition of the tall oil soap, the drilling fluid had a water loss by the A. P. I. filter method of 8 cc. The addition of the tall oil soap reduced the water loss of said drilling fluid to 1.5 cc.

The extreme importance of this reduction of water loss is readily appreciated by those skilled in the art. While critical values as to the tolerances in water loss that may be permitted without causing: serious trouble "will vary,; a great deal i depending upon the. formations being; drilled, lt I access? will be readily. appreciated. that cave-ins and Q other troubles will be less frequent withadrilling dam 01 low waterless..

- =,by the Marsh, funnel method, using 1500 cc. of

j drilling fluid in and one :quart out.= The viscosity '10 tall oil soap, and circulatingthe resulting drilling i after the addition or the soap was 38 seconds. I fluid in a well bore hole whereby a substantially Tall oil is a product of commerce which is also I impervious sheath ls i'ormed on the walls of said known as l-ignin liquor. It is'obtained by digest bore hole. I j I ingunder pressurechips t wood in caustic soda, '3. A water clay base drilling: fluid of suitable. Q 1 sulfite. liquor or other-chemicals. and crystallizing 5: viscosity for use in oil and gas: well drilling; said orgralnln-g out the-crude tall oil soap by'evapora I fluid. consisting of water. clay, endrmm: 1% to V tion-of the. waste liquor. 'I'hecrudesoapls then: 1 by volume basedon the drilling iluid or; 1 acidified toproducetall'oilr Tall oilmay'be're sodium tall oilsoam finedby processessuchasdlstillation, extraction I 4. .The'process' of circulating a drillingfluidin .and/or decantationj.- :Tall Icil; refined by such aw ll being-drilled for the production-atoll or I I methods, or unrefined, is suitable for use in ac- I see. to form a substantially water I impervious I cordance-with our invention.& Tall oil is.sold ccm- I I sheath on the wallsorth borehole Said 1 I mercially s above mentioned and: describedin- .-:and to lubricate the bit used in'the drillin oi. 1 I .the literature. t L .I I I. I -said welLwhichcomprisespreparing a claywater. I .The neutralizing: agents isuitableror' use with; g 'drilli ng fluid of suitable viscosity roruse' in all I I the tallzoilare such neutrallzlngagentsas hydrox I and gas well-drilling; and mlxins said fluid-withudes o;f' thealicali: metala-ior example; sndiumirom.1% to--%=by volume of sodiumta-ll oil 1 j I hy roxidapotasslum ydroxidet-ammnnium hy n; andcilclflating h 'resultmg' r sfl I; droxide, etc.,'the soluble :saltsof these metals. iin-awellbore hcleiwhere y aIsubstantl v m-* with, certain weak: .acids.;organic.basesand the -perjvious sheath is iormed on the walls'oi said I Q like. or any mixture of these .substances.- A'n bore 11018; f I

especially preferred-reagent .for: our purpose-is I. I J I I I gsodiumhydroxida. The neutralizing agentshould 1 ':1' ":"---2 2-EDWARD SAMUEL S I I preferably be present in an excessof thatrequir'ed I I II I neutralizethe tali zoll althoughlesser amounts 71*REFEREN3E5 CITED 2 preclluded' I I The ,fdllowlng references are of record inthe I The'product' frcmthereactloi; oi thetall oll me thi patentz II c I I I andzthe'neutralizingagent is ad edin-amounts I of mmaeoutwtm 10%:byvclumebf-the drilI- 'P I ing mud,- apreierred range being from 2% to 4 N b r Na Date he q ti y of o pr duct needed will 1,819,646 Loomis et al Aug. 18, 1931 vary with the drilling mud being treated as will 1,993,099 Hgdges Man 5, 1935 be appreciated by workers in the art. 2,209,59 games Jul 30, 1940 In order to reduce any foaming that may 00- 2,350,154 Dawson et al. May 30, 1944 our due to the vigorous agitation of the drilling 2,393,574 sommer Jan 22, 1946 mud, it may be desirable to add a small amount 2,430,039 Anderson Nov. 4, 1947 of alcohol, pine oil, kerosene, and the like to the 2,431,891 Rosencranse Dec. 2, 1947 drilling mud treated in accordance with our in- 2,4 1,433 Self Feb. 3, 1949 vention.

While our invention has been described, it is OTHER REFERENCES intended that the description shall be taken as illustrative and that changes may be made in the products and processes within the scope of the appended claims.

We claim as our invention:

1. A water clay base drilling fluid of suitable viscosity for use in oil and gas well drilling, said fluid consisting of water, clay, and from 1% to 10% by volume based on the drlling fluid of an alkali metal tall oil soap.

from 1% to 10%by voiumc' ofan-alkallmetal Searle, The Chemistry and Physics of Clays and Other Ceramic Materials, 1924 edition, pages 247-249.

Lawton et al., Chemical Treatment of Rotary Drilling Muds. Articles in Physics, vol. 2, No. 5, May 1932, pages 365-375, and vol. 3, No. 4, October 1932, pages -192.

Passler, The problem of improving drilling uzraudlsfhemical Abstracts, vol. 38, page 473, Jan.

2.-='1heprccessoicirculating a drilling fluid I I 1 in a well being :drilled for the production ol oil Q or gas to form a substantially water :lmpervicus I g sheath on ,thewalls or the bore hole oi'saidwell 1 I and to: lubrlcatethe bltuse'd in the drilling: of :1 :said well; which comprises preparing a'clay -water drilling fluid of suitable viscosity for use in oil j and'gas: welldrilling, and mixing said fl'uid with I 1 

